Subsea drilling assembly

ABSTRACT

An off-shore drilling assembly comprises a main body which has sheaves or pulleys so that it can be lowered from a vessel like a block. The main body performs a core drilling operation resting on the seabed. A traveller body can be pulled up and down between the vessel and the main body, fetching a core-containing core barrel inner tube from the bore-hole and delivering it to the vessel and returning it the emptied core barrel inner tube to the core barrel outer tube at the bottom of the bore-hole. The traveller body is firmly attached to the main body when it lands thereon.

O United States Patent 1 1 [111 3,741,320 Hilfing June 26, 1973 [54]SUBSEA DRILLING ASSEMBLY 3,491,842 1 1970 Delacour et a1. 175/6 M [75]Inventor: Karl Erik Hilfing, Stockholm, 3516503 6/1970 ayer at al 175/6Sweden Primary Examiner-Joseph H. McGlynn [73] Assignee: Atlas Copc.Aktiebolag, Nacka, Assistant ExaminerRichard E. Favreau SwedenAtt0mey-Munson & Fiddler [22] Filed: July 12, 1971 57 ABSTRACT 21App1.No.: 161,851 1 v An off-shore drilling assembly comprises a mambody which has sheaves or pulleys so that it can be lowered [52] US. Cl175/6, 175/45, 175/85, from a vessel like a block 175/52 51 Int. Cl E2lb19/14,E21b 47/02 mam Perfmms a drnmg resting on the seabed. A travellerbody can be pulled [58] Field of Search E21c/l9/00, 175/5, d b l h b d175,6 8 52 up an down etween t e vesse and t e mam o y, fetching acore-contammg core barrel inner tube from the bore-hole and deliveringit to the vessel and [56] References Cited returning it the emptied corebarrel inner tube to the UNITED STATES PATENTS core barrel outer tube atthe bottom of the bore-hole. 3,602,320 8/1971 Howard 175/8 The travellerbody is firmly attached to the main body 2,676,787 4/1954 Johnson 175 7when it lands thereon 3,408,822 11/1968 Chate et al. 166/.5 X 3,442,3395/1969 Williamson 175/6 19 Claims, 25 Drawing Figures PAIENIEDJUIIZB umSREEIBNQ IN VENTUR.

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PATENIEBJum ms SHEEISUFQ l N V15 NTOR SUBSEA DRILLING ASSEMBLY Thisinvention relates to an off-shore drilling assembly of the kind whichhas a main body arranged to'be lowered from a vessel or another floatingstructure and which, resting on the seabed, is arranged to perform acore drilling operation which includes successive addition of stringelements to the drill string. Such drilling assemblies are very suitablefor surveying purposes and especially for surveying and prospecting thecontinental shelf.

It is an object of the invention to provide a drilling assembly of thekind referred to in which the core formed during the drilling is broughtup to the surface before drilling continues after each addition of adrill string element to the drill string. Other objects will be apparentfrom the detailed description and claims.

In the drawings:

FIG. 1 is a perspective view of a drilling assembly located foroff-shore drilling.

FIG. 2 is a side elevational view of a body shown in FIG. 1 and standingon the sea-bed.

FIG. 3 is a fragmentary section on line 3-3 in FIG. 2.

FIG. 4a is an enlarged fragmentary section on line 4-4 in FIG. 2. I 1

FIG. 4b is the same section as FIG. 4a but showing some details inanother position.

FIG. 6 is a fragmentary section on line 6-6 in FIG.

FIG. 7 shows a detail indicated in FIG. 6.

FIG. 8 is an elevational view like FIG. 2 but showing only the upperportion of the body, a traveller body being also shown.

FIG. 9 is a perspective view showing the upper portions of the bodyshown in FIG. 2, the uppermost portion, however, being cut away.

FIG. 10 shows some details shown in FIG. 8.

FIG. 11 is a view on line 11-11 in FIG. 8.

FIG. 12 is a section through a traveller body shown in FIGS. 8 and 11and the upper portion of the body shown in FIG. 2.

FIG. 13 is a perspective view of a rotation unit (drill) located at theupper portion of the body in FIG. 2.

FIG. 14 shows some details of FIG. 13 in another position.

FIG. 15 is a perspective view partly in section of a chuck unit which ispart of the body'shown in FIG. 2.

FIG. 16 is a fragmentary section taken along the line l6-l6 in FIG. 2drawn to an enlarged scale and showing a clamp.

FIG. 17 is the same section as FIG. 16 but the details are shown inanother position.

FIG. 18 is a'fragmentary section taken along the line l8-18 in FIG. 2,showing drawn to an enlarged scale a shutter.

FIG. 19 is the same section asFIG. 18 but some details are shown inanother position.

FIG. 20 is a fragmentary view taken along the line 20-20 in FIG. 2,drawn to an enlarged scale showing a casing tube clamp.

FIG. 21 is a fragmentary section taken along the line 2121 in FIG. 20.

FIG. 22, is another fragmentary section along line 21-21 in FIG. 20.

FIG. 23 shows a detail of FIG. 21.

FIG. 24 is a diagrammatic, fragmentary version of FIG. 2.

FIG. 5 is an enlarged section through a leg of the body shown in FIG. 2.

In FIG. 1 there is shown a main body 11 having a tripod frame with legs12-14 which supports it on the sea bottom. The main body 11 has beenlowered from a ship 15 and is suspended by two lines 16,17 which form asingle line which engage sheaves or pulleys on the main body; and atraveller body 18, suspended by another line 19, is shown on its waybetween the ship and the main body along the lines 16,17. An electriccable 20 contains electric power lines for supplying the main body withelectric power, and it contains also a large number of electric checklines and control lines so that the drilling operation can be completelycontrolled from the ship.

The electric cable is attached at 21 to the leg 12 and since the line16,17 and the cable 20 are spaced apart where they are connected to theship, this arrangement will prevent the main body 1 1 from rotating whenbeing lowered from the ship. However, this arrangement is sometimes notsufficient when the main body 11 is to be lowered to deeper areas and apropeller 22 driven by a reversible hydraulic motor is thereforeutilized for stabilizing the main body during the lowering. The

main body is preferably provided with a direction sensing means such asa gyroscope or a compass indicated by 23 in FIG. 6 and the direction isindicated on board the ship from where the rotation of the propeller 22is controlled.

The triod main body has an annular housing 24 which has two partitions25,26 (FIG. 6). These partitions divide the housing in a chamber 27which is open to the surrounding water and a watertight chamber 28 whichis filled with oil and has an elastomeric cover 29. Because of theflexible cover 29, there will always be the same pressure in the oilinside the chamber 28 as in the surrounding water and the walls of thehousing 24 can therefore be thin.

The legs 12-14 consist of double acting hydraulic jacks with shoes 30universally mounted on the pistons of the jacks (FIG. 4b). The bottomsof the shoes have holes through which water can be pumped out so as tofacilitate the lifting of the main body if the legs have sunk into thesea-bottom. The pressure in the'pressure chambers of the jacks, that is,the load on the legs are sensed and transmitted electrically to .theship so that the risk of tilting of the main body is on a receiverindicated on board the ship. A circular revolving magazine 31 for drillrods (drill pipe lengths) extends into the central opening of theannular housing 24 and it is surrounded by a streamlined casing 32 whichis freely rotatable and has the only functions of reducing the dynamicforces on the main body.

A drill unit 34 is reciprocable by means of a doubleacting hydraulicfeed jack 35 which is mounted in the tripod main frame. Articulatedstruts 36 are arranged to take up the reaction forces from the rotationand transmit the forces to the feed jack 35. The drill unit 34 is shownin detail in FIG. 13 and it has a double-acting hydraulic rotation motor38 which, preferably, is a positive displacement motor e.g., an axialpiston pump. The motor rotates a geared bushing 39 for a drive rod 40 bymeans of a drive gear 41. The bushing 39 and the drive rod 40 rotateconjointly because of a key 42, and axial forces are transmitted betweenthe bushing 39 and the drive rod 40 by means of radial pins 43 which arestrong enough to resist the axial forces during operation but which willbreak if the drill string by some reason becomes stuck so that the mainbody has to be brought up to the surface leaving the drill pipe (thedrill string) in the bore hole. In this case the drive rod 40 willremain on top of the drill string.

A hydraulic jack 44 is coupled to a member 45 which has two teeth whichare free from engagement with the teeth of the bushing 39 when the jackis in its extended position as shown in FIG. 13. When the jack is beingretracted, however, the toothed member 45 moves into engagement with thebushing 39 as shown in FIG. 14 and since the jack 44 and the rotationmotor 38 can be operated simultaneously, the torque will be great enoughto ensure breaking of a screw-joint between two drill string lengths orthe screw joint between the drive rod 40 and the drill string. A coilspring 46 is provided so as to yield if the teeth of the member 45should face two teeth on the bushing gear.

A freely rotating double chuck unit 47 is mounted on the feed jack 35just above the magazine 31 and the casing 32, and it is shown inperspective in FIG. drawn to an enlarged scale. It has two independentlyactuated chucks, each having three jaws 48,49 carried by hydraulicallyactuated pistons 50,51. The chuck unit 47 can be locked against rotationby means of a hydraulic jack 52 which has a toothed member 53 forengaging a toothed ring 54 of the chuck unit. Below the annular housing24 inside the tripod frame, there is another chuck or clamp 55 (FIG. 16)for holding the drill pipe. The clamp, 55 is actuatedby means of twobydraulic jacks 56,57, and it can be opened wide by means of a thirdjack 58 so as to allow insertion of a casing pipe as will be described.Heavy springs 59 will ensure the holding of the drill pipe even if thejacks 56,57 should fail. Below the clamp 55 there is a casing clamp 60(FIG. 20) with dogs 61,62 which are opened by spring bias and actuatedto grip by means of a by draulic pull jack 63. A rubber plate 64 isarranged so as to prevent mud and sand from flowing directly into theclamps 60,55. The revolving magazine 31 is carried by the feed jack 35which it surrounds and it comprises an upper transverse plate 65 and alower transverse plate 67 which are interconnected. A shutter 68actuated by a hydraulic jack 69 is arranged under the lower plate 67 ofthe magazine and in FIG. 18 it is shown open and in FIG. 19 closed. Theshutter 68 moves into an opening in a stationary annular plate 70 whichforms an abutment for a number of drill pipe lengths, the core barrel,and two casing tubes which all are inserted through holes in thetransverse plates 65,67 of the magazine. The magazine 31 can be rotatedstepwise by means of a hydraulic jack 71 as can be seen from FIGS. 4aand 4b.

The two guide lines 16,17 are shown as a single line which pass over twosheaves or pulleys 72,73 and two guide members 74 which are mounted onthe drill unit 34 for guiding the line 16,17 and also for guiding thetraveller body in its seating (FIGS. 8 and 10). The chamber in the drillunit, in which the drive gear 41 of the rotation motor, the bushing 39for the drive rod 40 and the jack 44 are located, is filled with oil andclosed by a seat member 76 of the drill unit. The seat member 76 is cutaway in FIG. 8 along line 88 in FIG. 12. The drive rod 40 extends intothe seat member and is sealed off by suitable sealing rings. The seatmember 76 of the drill unit forms a seat for the traveller body 18 whichcomprises an elongated cylindrical portion 77 and a body portion 78 witha frusto-conical rubber sleave 79 and four radial arms 80. Thecylindrical portion 77 of the traveller body is double-walled (FIG. 12)and the inner cylindrical wall 81 forms a core barrel for a tubularretrieving member 82 which is suspended in the line 19. The travellerbody 18 is fastened at 86 to the line part 16 and runs at 87 along theline part 17 (FIG. 11) and it can thus be pulled up and down between theship and the main body 11 by means of the line 16,17. A ring 88 isfastened to the seat member 76 and if the traveller body 18 is not invertical position when landing on the main body, one of the arms of thetraveller body will abut the ring 88 so as to be pulled upright by theline 16,17 and thus facilitates seating.

A flush-water pump 89 is located in the water filled chamber 27 of thehousing 24 of the main body and its intake opening for sea-water isconnected to the chamber 90 which is be defined between the seat member76, the traveller body 18, the sleeve 79 of the traveller body and anannular sealing ring 91 fastened to the seat member. A back pressurecheck valve 92 is arranged so as to admit sea water into the suctionchamber 90 while still maintaining a partial vacuum in the suctionchamber. The traveller 18 will therefore be firmly attached to the mainbody by suction as it lands. The outlet 93 of the flush-water pump 89 isconnected to a valve 94 in the seat member. The valve 94 is biased intoa position in which it admits the water from the pump into a passage 95which leads to the cylindrical space above the drive rod 40 so that theflush water is forced into the drive rod during drilling. However, whenthe traveller body 18 is sealed properly, it actuates a lever system 96so that the valve 94 shifts into the position shown in FIG. 12 in whichposition the water from the flush water pump 89 is admitted throughanother passage 97 and up between the walls of the cylindrical portionof the traveller body to the space above the retrieving member 82 whichis thus pumped downward through the drive rod 40 and the drill pipe.Simultaneously with the valve 94 being shifted, a shut-off valve 98 isshifted to its open position in which it is shown in FIG. 12 so as topermit the retrieving member 82 to move into and through the drive rod.It is to be understood that the valves 94,98 and their leverages areshown very schematically and, preferably, the valves are interconnectedas a single valve. The struts 36 can preferably be used as parts of theconduits for conveying the intake water from the drill unit to the waterpump 89 and the outlet water from the pump 89 to the drill unit.

In FIG. 12 the retrieving member 82 is shown carrying an inner tubeassembly 98 which has a pair of jaws 99 gripping a spearformed head 100of the retrieving member. The retrieving member and the inner tubeassembly 98 can be connected and disconnected and the inner tubeassembly can be latched to the outer tube of the core barrel which outertube carries a diamond core bit or a core bit with carbide inserts. Themechanisms for interconnection and disconnection are shown in detail butreference is instead made to U. S. specification 3,567,269.

The flush water pump 89 in the water filled chamber 27 of the housing 24is driven by a chain drive by an electric motor 101 in the oil filledchamber. In the oil filled chamber, there are also a hydraulic pump 102,for the hydrostatic drive of the rotation motor 38, a hydraulic pump 103for the hydraulic legs 12-12 and the propeller 22, and a hydraulic pump113 for the feed jack 35. The hydraulic pumps are driven by electricmotors which have no casing but rotate directly in the oil and the pumpstake their oil directly from the oil surrounding them. When the feedmotor 35 is operated, the amount of low pressure oil will vary and thisconsiderable fluctuation is taken up by the flexible cover 29.

In the water-filled chamber there is a small air chamber 110 with aninclination indicator 111 shown in FIG. 7 and having threeinterconnecting glass pipes partly filled with a conducting liquid andorientated towards the three legs 12-14. Four electrodes are connectedto control lines in the cable so that the inclination of the main body11 is indicated on board the ship, and the level of the liquid can bevaried at will by means of a motor actuated .piston 112.

The operation of the drilling assembly will now be described withreference chiefly to FIG. 24 in which the shutter 68, the clamp or chuck55, the casing clamp 60, and the chuck unit 47 are shown schematically.The magazine 31 is not shown in this figure.

When the main body 11 has been positioned on the seabed, the drill unit34 is at first raised and the magazine 31 is turned until a casing tube105 in the magazine is in alignment with the drive rod 40 and thechucks. The casing tube has an annular drill bit at its lower end and anadapter 104 at its upper end. The adapter is affixed to the casing tubeby a bayonet joint and its upper end is threaded so that it can beconnected to the drive rod 40. The casing tube 105 and its adapter104'is shown in FIG. 21 and the upper part of the magazine is partlyshown. The upper plate 65 of the magazine has a bushing with a number ofrubber rings 107 which hold the adapter 104. The drill pipe clamp 55 isopened wide as in FIG. 17 and the shutter 68 and the casing clamp 60 areopened so as to permit introduction of the casing tube 105. The drillunit 34 is now lowered and the drive rod 40 is rotated so that the driverod is screwed onto the adapter and the casing tube is drilled down intothe seabed until an annular recess 106 in the upper part of the casingtube is just opposite the casing clamp. The casing clamp 60 is nowactuated to hold the casing tube 105 as shown in FIG. 22 until thedrilling operation is finished thereby anchoring the main body 11 in thecasing tube. The drive rod 40 is turned backwards slightly and the drill34 is then raised so that the bayonet joint between the adapter 104 andthe casing tube 105 is disconnected. The adapter 104 is now clamped inthe clamp 55 and the hydraulic jack 44 of the drill unit (FIG. 13) 13)is actuated to break the screw joint between the drive rod 40 and theadapter 104. The jack turns the drive rod 40 only about and breakstherefore the joint without completely disconnecting it. The drill israised until the adapter 104 becomes stuck in the rubber rings 107 andthe drive rod is rotated backwards so that it is disconnected from theadapter 104. The drill 34 is now raised to its upper end position,leaving the adapter 104 in the magazine as shown in FIG. 23.

Since the seabed can vary a great deal, the magazine 31 is normallyprovided with two casing tubes 105 with adapters 104. The two casingtubes have different length and the operator selects the one which hebelieves would suit the seabed best. The other is still in the magazineand will not be used.

The shutter 68 is now closed and the magazine 31 is turned a step sothat the first drill pipe element the outer tube of the double tube'corebarrel and the coring drill bit attached to this outer tube becomesaligned with the chucks and the clamps. The drill 34 is slowly loweredwith the drive rod 40 rotating and, with the core barrel outer tuberesting on the shutter 68, the drive rod will be screwed onto the corebarrel outer tube, the magazine providing enough torque resistance. Now,the shutter 68 can be opened and drilling through the casing tubestarted. When the joint between the core barrel and the drive rod 40 hasmoved to just below the shutter 68, the core barrel is clamped in clamp55, and the joint is broken and disconnected by means of the jack 44 andthe rotation motor 38. The drill 34 is then raised, the magazine 31turned another step and another drill pipe length is first screwed tothe drive rod 40 and then to the core barrel.

Every time the core-receiving inner tube 98 of the core barrel is filledwith a core or the core breaks and jams, the core barrel inner tubemoves slightly upwardly in the core barrel outer tube and actuates anonillustrated rubber ring at its upper end to block the flushing fluid.This results in a rise'in the pressure of the flushing fluid, and sincethe pressure of the flushing fluid is indicated on the instrument panelon board the ship, the operator will always know when the core barrelinner tube 98 must be emptied. Then he stops the drilling and pulls thetraveller body 18 down by means of the line 16,17. When the travellerbody 18 seats on the drill 34, the retrieving member 82 with the spear100 will automatically be pumped down through the drill pipe to the corebarrel as described and the spear 100 will automatically latch the jaws99 on the head of the inner tube. Then, when the line 19 is pulled, theinner tube 98 is freed from the outer tube simultaneously with the corebeing wedged off at its lower end. The retrieving member 82 with theinner tube is now lifted by the line 19 into the top position in thetraveller body 18. During this lifting operation the fluid pressure fromthe flush water pump 89 can be maintained above the retrieving memberwhich in this case should be provided with a relief valve for permittinga flow therethrough.

A solenoid valve 107 is now actuated to connect the outlet and the inletof the pump 89 and because of leakage through the back pressure valve92, the pressure in the suction chamber 90 will rise to the ambientpressure and the traveller body 18 can be pulled to the surface by meansof the line 16,17 or the line 19. The inner tube 98 is emptied on boardthe ship, the traveller body 18 is again pulled down to seat on thedrill 34, and the retrieving member 82 is pumped down into the bore holeto deliver the inner tube which automatically latches to the outer tubeof the core barrel and at the same time is disconnected from theretrieving member. The retrieving member 82 is again pulled to thetraveller body and the traveller body pulled to the surface or half wayup to the surface where it is suspended until the inner tube again mustbe emptied.

The traveller body 18 can be used also for supplying the magazine 31with drill pipe lengths when more drill pipe lengths are needed than canbe stored in the magazine.

When the desired depth of the bore hole is reached, the drill pipelengths are brought'back to the magazine. To this end, the drill 34 israised to its position in FIG.

24 in which the joint between the drive rod 40 and the uppermost drillpipe length 108 is in the middle of the double chuck 47 as in FIG. 24.The two sets of jaws of the double chuck are then actuated so as to gripand the chuck unit remains free to rotate. The break cylinder 44 isactuated to break but not completely disconnect the joint between theuppermost drill pipe length 108 and the remainder of the drill pipe 109which is firmly held by the clamp 55, the double chuck 47 holding thejoint between the drive rod 4 and the drill pipe length 108. Now thedrill is lowered until the joint between the pipe length 108 and theremainder of the drill pipe 109 isjust above the clamp 55, and thisclamp is actuated to hold the drill pipe 109 while the drill pipe length108 is unscrewed from the drill pipe 109 by means of the rotation motor38. The double chuck 47 is axially movable to a limited extent slightlymore than the length of the joint so as to'allow this unscrewing. Thedrill 34 is now raised until the joint between the drive rod 40 and thepipelength 108 is again located in the middle of the double chuck 47 andthe lower set of jaws 49 of the chuck is actuated to hold the pipelength 108 while the break cylinder 44 and the rotation motor 38 areused to unscrew the drive. rod 40, the chuck being prevented fromrotating by means of the jack 52. The shutter 68 is now closed and thepipe length 108 falls down on the shutter when the jaws of the doublechuck 47 are released.

The magazine can now be turned another step with the pipe length 108remaining in it. The drive rod 40 can be lowered through the magazine,screwed onto the drill pipe, and again raised to withdraw the drillpipe; and thus another pipe length can be inserted in the magazine. Whenall the pipe lengths have been inserted in the magazine, the magazine isturned until the casing adapter 104 is aligned with the drive rod 40,and the drive rod is screwed onto the adapter. The casing tube 105 isnow pulled into the magazine and the joint between the adapter 104 andthe drive rod 40 is disconnected.

The entire main body can now be lifted and positioned for drillinganother bore hole without being lifted to the surface.

it is to be understood that the invention is not limited to thedescribed embodiment but can be varied in many ways within the scope ofthe claims.

What I claim is:

1. In an off-shore drilling assembly: a main body adapted to bepositioned on the sea bottom and including an axially movable drill forrotating a drill string ing a core-containing inner tube assembly fromthe borehole.

3. A drilling assembly as claimed in claim 1 in which said flexibleguide comprises at least two lines. for lowering the main body from thefloating structure to the sea bottom, means for sensing the horizontaldirection are arranged on the main body, and a propelling means isarranged on the main body for preventing rotation of the main bodyduring said lowering of "the main body.

4. A drill assembly as claimed in claim 1 in which a flush-water pumphas its intake of sea-water at the upper portion of the drill, saidtraveller body and said upper portion of the drill define a closedsuction chamber when the traveller body is seated on the drill, saidinlet of seawater ends in said closed suction chamber, and aback-pressure check valve is arranged to permit sea-water to said closedchamber, said flush-water pump thereby providing said anchoring of thetraveller body to the main body.

5. A drilling assembly as claimed in claim 1 in which the coreretrieving device is suspended in a wire, a flush water pump is arrangedso as to supply flush water to the drill string, a valve is arranged inthe flush water supply conduit, and the traveller body is arrangedtoshift the valve into connecting the flush water pump outlet to a spacein said travelling body at the rear of said retrieving device so thatsaidretrieving device is pumped down into the bore hole when the travelbody seats on the drill.

6. A drilling assembly as claimed in claim 1 in which said feedingdevice comprises a vertical double-acting which includes a core barrelassembly provided with a A detachable and replacable inner tube assemblyfor receiving and retaining a core, and a feeding device for displacingthe drill axially, and a traveller body adapted to travel between afloating structure and the main body along a flexible guide, carrying acore-containing core barrel inner tube assembly from the main body tothe floating structure and an empty core barrel inner tube assembly fromthe floating structure to the main body, means for releasably anchoringthe traveller body to said main body, and a device in the traveller bodyarranged to be lowered from the traveller body into the borehole forretrieving a core-containing inner tube assembly from the core barrel.

2. A drilling assembly as claimed in claim 1 in which the retrievingdevice is adapted to lower an empty inner tube assembly into theborehole alternatively to fetchhydraulic jack which is mounted on themain body and carries the drill axiallymovably.

7. A drilling assembly as claimed in claim 6 in which an arm structurewith an elbow-joint is pivotably connected between the unmovable part ofthe main body and the drill.

8. A drilling assembly as claimed in claim 6 in which the drill includesa drive rod onto the lower end of which a drill string element can bescrewed, and a reversible rotation motor for rotating the drive rod, andthe main body further comprises a freely rotatable chuck unit having twoindependently fluid actuated sets of chuck jaws, the upper of the setsof jaws being adapted for gripping the drive rod and the lower of thesets of jaws for gripping a drill string element when such a drillstring element has been screwed to the lower end of the drive rod andthe drill is in an upper position, said chuck unit being axiallymovable, a fluid actuated means for locking said chuck unit againstrotation, a magazine below said chuck housing and arranged to store acasing tube and a number of drill string elements, a drill string clampbelow said magazine, and a casing tube clamp below said drill stringclamp.

9. A drilling assembly as claimed in claim 1 in which the main body isprovided with sheave means and said flexible guide comprises a linedeviated over the sheave means so that the main body can be lowered fromthe floating structure and lifted to the floating structure in the line.

10. A drilling assembly as claimed in claim 9 inwhich the traveller bodyis adapted to be clamped to one part of said line and guided on theother part so that it can be pulled up and down between the floatingstructure and the main body by means of the line.

11. In an off-shore drilling assembly: a remote controlled main bodyarranged to be positioned on the sea bottom from a floating structureand including a drilling device for rotating and feeding a drill string,a watertight housing filled with oil and being a part of the main body,an oil pump in the housing taking oil directly from the oil surroundingit and delivering pressure oil to a hydraulic motor, means for returninglow pressure oil to the housing from the hydraulic motor, an electricmotor in the housing driving the oil pump, an electric power line fromthe floating structure to the electric motor in the housing, and an oilaccumulating device taking up the fluctuations in volume of the lowpressure oil.

12. A drilling assembly as claimed in claim 11 in which the accumulatingdevice is a flexible wall member of the housing.

13. A drilling assembly as claimed in claim 11 in which at least one ofthe hydraulic jacks outside said watertight housing are supplied withpressure oil from said oil pump in the housing.

14. A drilling assembly as claimed in claim 11 in which the main bodyhas three adjustable legs, and the housing is annular so as to allow thedrill string to extend through the housing into the bore hole.

15. A drilling assembly as claimed in claim 14 in which the legs areadjustable by means of pressure oil delivered from said oil pump.

16. A drilling assembly as claimed in claim 14 in which a revolvingmagazine for a plurality of drill string elements extends into theopening of the housing.

17. A drilling apparatus arranged to be positioned on the sea bottom,lowered from a floating structure, and comprising: a frame work, meansfor supporting the frame work on the sea-bed, an axially movable drillincluding a drive rod onto the lower end of which a drill rod length canbe screwed and a reversible rotation motor for rotating the drive rod, afeed motor for displacing the drill axially, a rotatable chuck unitmounted on said frame work and having two independently fluid actuatedsets of chuck jaws, an upper of the sets of jaws being adapted forgripping said drive rod and the lower of the sets of jaws for gripping adrill rod length when such a drill rod length is screwed to the lowerend of the drive rod and the drill is in an upper position, said chuckunit being axially movable, a fluid actuated means for locking saidchuck unit against rotation, a magazine below said chuck housing andarranged to store a casing tube and a number of drill rods, a drill rodclamp below said magazine, and a casing tube clamp below said drill rodclamp.

18. A drilling apparatus as claimed in claim 17 in which the feed motoris an upright double acting hydraulic feed jack which is a part of theframe work, and the drill is mounted on the piston rod of the feed jack.

19. A drilling apparatus as claimed in claim 18 in which articulatedstruts for taking up reaction torque is mounted between the cylinder ofthe feed jack and the drill.

UNITED STATES PATENTYOFFICE CERTIFICATE OF- QQRRECTION Patent 110.3,141,320 f Dated June 26, 1973 Inventor(s) Karl Erik'Hilfing I It iscertified that error-appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Col. 4, line 4; "core" has been cancelled Col. 4, lines 42 and 44, "98"has been changed to "94' 1 211 Fig. 1 2 the shut off valve numbered"9-8" in the lower right corner has been renumbered "--94--.

Signed and sealed this 7th day of January 1975.

(SEAL) Attest:

'McCOYM. GIBSQN JR. c. MARSHALL DANN Attesting Officer I Commissioner ofPatents

1. In an off-shore drilling assembly: a main body adapted to bepositioned on the sea bottom and including an axially movable drill forrotating a drill string which includes a core barrel assembly providedwith a detachable and replacable inner tube assembly for receiving andretaining a core, and a feeding device for displacing the drill axially,and a traveller body adapted to travel between a floating structure andthe main body along a flexible guide, carrying a core-containing corebarrel inner tube assembly from the main body to the floating structureand an empty core barrel inner tube assembly from the floating structureto the main body, means for releasably anchoring the traveller body tosaid main body, and a device in the traveller body arranged to belowered from the traveller body into the borehole for retrieving acore-containing inner tube assembly from the core barrel.
 2. A drillingassembly as claimed in claim 1 in which the retrieving device is adaptedto lower an empty inner tube assembly into the borehole alternatively tofetching a core-containing inner tube assembly from the borehole.
 3. Adrilling assembly as claimed in claim 1 in which said flexible guidecomprises at least two lines for lowering the main body from thefloating structure to the sea bottom, means for sensing the horizontaldirection are arranged on the main body, and a propelling means isarranged on the main body for preventing rotation of the main bodyduring said lowering of the main body.
 4. A drill assembly as claimed inclaim 1 in which a flush-water pump has its intake of sea-water at theupper portion of the drill, said traveller body and said upper portionof the drill define a closed suction chamber when the traveller body isseated on the drill, said inlet of seawater ends in said closed suctionchamber, and a back-pressure check valve is arranged to permit sea-waterto said closed chamber, said flush-water pump thereby providing saidanchoring of the traveller body to the main body.
 5. A drilling assemblyas claimed in claim 1 in which the core retrieving device is suspendedin a wire, a flush water pump is arranged so as to supply flush water tothe drill string, a valve is arranged in the flush water supply conduit,and the traveller body is arranged to shift the valve into connectingthe flush water pump outlet to a space in said travelling body at therear of said retrieving device so that said retrieving device is pumpeddown into the bore hole when the travel body seats on the drill.
 6. Adrilling assembly as claimed in claim 1 in which said feeding devicecomprises a vertical double-acting hydraulic jack which is mounted onthe main body and carries the drill axially movably.
 7. A drillingassembly as claimed in claim 6 in which an arm structure with anelbow-joint is pivotably connected between the unmovable part of themain body and the drill.
 8. A drilling assembly as claimed in claim 6 inwhich the drill includes a drive rod onto the lower end of which a drillstring element can be screwed, and a reversible rotation motor forrotating the drive rod, and the main body further comprises a freelyrotatable chuck unit having two independently fluid actuated sets ofchuck jaws, the upper of the sets of jaws being adapted for gripping thedrive rod and the lower of the sets of jaws for gripping a drill stringelement when such a drill string element has been screwed to the lowerend of the drive rod and the drill is in an upper position, said chuckunit being axially movable, a fluid actuated means for locking saidchuck unit against rotation, a magazine below said chuck housing andarranged to store a casing tube and a number of drill string elements, adrill string clamp below said magazine, and a casing tube clamp belowsaid drill string clamp.
 9. A drilling assembly as claimed in claim 1 inwhich the main body is provided with sheave means and said flexibleguide comprises a line deviated over the sheave means so that the mainbody can be lowered from the floating structure and lifted to thefloating structure in the line.
 10. A drilling assembly as claimed inclaim 9 in which the traveller body is adapted to be clamped to one partof said line and guided on the other part so that it can be pulled upand down between the floating structure and the main body by means ofthe line.
 11. In an off-shore drilling assembly: a remote controlledmain body arranged to be positioned on the sea bottom from a floatingstructure and including a drilling device for rotating and feeding adrill string, a watertight housing filled with oil and being a part ofthe main body, an oil pump in the housing taking oil directly from theoil surrounding it and delivering pressure oil to a hydraulic motor,means for returning low pressure oil to the housing from the hydraulicmotor, an electric motor in the housing driving the oil pump, anelectric power line from the floating structure to the electric motor inthe housing, and an oil accumulating device taking up the fluctuationsin volume of the low pressure oil.
 12. A drilling assembly as claimed inclaim 11 in which the accumulating device is a flexible wall member ofthe housing.
 13. A drilling assembly as claimed in claim 11 in which atleast one of the hydraulic jacks outside said watertight housing aresupplied with pressure oil from said oil pump in the housing.
 14. Adrilling assembly as claimed in claim 11 in which the main body hasthree adjustable legs, and the housing is annular so as to allow thedrill string to extend through the housing into the bore hole.
 15. Adrilling assembly as claimed in claim 14 in which the legs areadjustable by means of pressure oil delivered from said oil pump.
 16. Adrilling assembly as claimed in claim 14 in which a revolving magazinefor a plurality of drill string elements extends into the opening of thehousing.
 17. A drilling apparatus arranged to be positioned on the seabottom, lowered from a floating structure, and comprising: a frame work,means for supporting the frame work on the sea-bed, an axially movabledrill including a drive rod onto the lower end of which a drill rodlength can be screwed and a reversible rotation motor for rotating thedrive rod, a feed motor for displacing the drill axially, a rotatablechuck unit mounted on said frame work and having two independently fluidactuated sets of chuck jaws, an upper of the sets of jaws being adaptedfor gripping said drive rod and the lower of the sets of jaws forgripping a drill rod length when such a drill rod length is screwed tothe lower end of the drive rod and the drill is in an upper position,said chuck unit being axially movable, a fluid actuated means forlocking said chuck unit against rotation, a magazine below said chuckhousing and arranged to store a casing tube and a number of drill rods,a drill rod clamp below said magazine, and a casing tube clamp belowsaid drill rod clamp.
 18. A drilling apparatus as claimed in claim 17 inwhich the feed motor is an upright double acting hydraulic feed jackwhich is a part of the frame work, and the drill is mounted on thepiston rod of the feed jack.
 19. A drilling apparatus as claimed inclaim 18 in which articulated struts for taking up reaction torque ismounted between the cylinder of the feed jack and the drill.